Bradycardia glycosides causing

Digitalis glycosides cause an influx of extracellular calcium and an accumulation of extracellular potassium. The increased levels of extracellular potassium decrease the rate of repolarization of the cardiac cell. Thus, as levels of the drug approach the toxic range, accumulated extracellular potassium causes a lengthening of phase 3 of the cardiac action potential and an increase in the length of time between depolarizations. Thus, bradycardia is seen. 

MEFLOQUINE CARDIAC GLYCOSIDES -DIGOXIN Risk of bradycardia Uncertain probably additive effect mefloquine can cause AV block Monitor PR and ECG closely... 

Red squill contains many cardiac glycosides, the most prominent being scillaren A and scilliroside. These glycosides produce digitalis-like effects when ingested and, like digitalis, inhibit Na/K ATPase, block AV conduction, and cause sinus bradycardia. 

All cardiac glycosides preparations have the potential to cause toxicity. Because the minimal toxic dose of the glycosides is only two- to threefold the therapeutic dose, intoxication is quite common. In mild to moderate toxicity, the common symptoms are anorexia, nausea and vomiting, muscular weakness, bradycardia, and ventricular premature contractions. The nausea is a result of excitation of the chemoreceptor trigger zone in the medulla. In severe toxicity, the common symptoms are blurred vision, disorientation, diarrhea, ventricular tachycardia, and AV block, which may progress into ventricular fibrillation. It generally is accepted that the toxicity of the cardiac glycosides results from inhibition of the Na /K -ATPase pump, which results in increased intracellular levels of Ca ". Hypokalemia (decreased potassium), which can be induced by coadministration of... 

Serum digoxin levels are increased by about 40% by verapamil 160 mg daify, and by about 70% by verapamil 240 mg daily. Digoxin toxicity may develop if the dosage is not reduced. Deaths have occurred. Verapamil causes a rise of about 35% in digitoxin levels. There is a risk of additive bradycardia and conduction disturbances when cardiac glycosides are given with verapamil... 

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